Torque wrench indicator and compensator



July 9, 1968 J. B. H I L I ..ER

TORQUE WRENCH INDICATOR AND COMPENSATOR Filed April 4, 1966 INVENTOR.

United States Patent 3,391,573 TORQUE WRENCH INDICATOR AND COMPENSATOR John B. Hiller, Rte. 5, Box 5445, Albuquerque, N. Mex. 87116 Filed Apr. 4, 1966, Ser. No. 539,820 4 Claims. (Cl. 73-139) ABSTRACT OF THE DISCLOSURE A conventional torque wrench having a lateral scale marked in torque units is fitted with a longitudinally adjustable pointer and a longitudinal scale marked in length units, allowing direct reading of torque when an extension lever arm is used on the wrench, by compensating for the lever arm length with an adjustment of the pointer.

This invention relates to improvements in torque measuring and indicating wrenches, and more particularly, the invention is concerned with a wrench of the type characterized by a resilient beam by which the torsional forces are transmitted to a part to be turned. The part being turned will exert a torque equal and opposite to the torque applied by the wrench. The deflection of the beam will vary directly as the magnitude of this torque and hence lends itself to be translatable into appropriate torque units.

Some torque measuring operations require that adaptors be attached to the torque wrenches, thereby changing the effective torque wrench lever length to a value different from that provided by the calibrated indicator or scale aflixed to the torque wrench. The incorrect installation of an adaptor on a torque wrench or the incorrect calculation of a standard torque wrench when used in conjunction with such an adaptor may cause under or over-tightening, and possible failure of a fastener or other device being torqued. Hence, when an adaptor, such as a lever arm extension is used with a conventional torque wrench, the torque indicated on the scale of the wrench generally does not represent the true or actual torque applied.

An object of this invention is to maintain the direct reading capability of a torque wrench when it is used with an adaptor including a lever arm extension.

The torque range or capacity of a given torque wrench increases as the in-line lever arm extension length increases. In a conventional torque wrench, the maximum torque capability for a given lever arm extension length must be calculated or a multiplication factor used in each case.

Another object of this invention is to provide a torque wrench that may be used with a lever arm extension and at the same time eliminate any calculations.

Another object of this invention is to provide a torque wrench having a direct reading capability when used with a lever arm extension that requires no auxiliary equipment foreign to the wrench per se.

A still further object of this invention is to provide a torque wrench which incorporates means thereon by which direct torque readings may be obtained without the use of cumbersome support equipment when the wrench is used with or without an extension or an adaptor.

These and other objects, features and advantages of the present invention will become more obvious from the following description when taken in connection with the accompanying drawing which shows, for purpose of illustration only, the present invention, and wherein:

FIG. 1 shows a plan View of one of my improved torque wrenches, showing the indicating needle in central position.

FIG. 2 is a fragmentary plan view of the improved 3,391,573 Patented July 9, 1968 ICE torque wrench, having a modified type of indicator needle adjustment scale.

FIG. 3 is a part sectional side elevation of the torque wrench, showing details of the compensator.

While there is shown herein the improved features embodied in a specific type of manually operable torque wrench having a square shank which is attachable to various type work engaging sockets, it is not intended to restrict the scope of this invention by virtue of such a specific embodiment, nor is it intended to restrict the invention by the use of specific descriptive terms.

Referring now to the drawing, the present improved torque wrench includes a resilient beam 30 which carries a head 32 at one extremity and a handle 12 interconnected by yoke 16 to the other extremity. Integrally formed as a portion of head 32 is lever arm compensator generally indicated by numeral 10 and having a rigid arm 38 separated from resilient beam 30 by a slot 39. Adjustably affixed to the rigid arm 38 is a pointer 40 having a reduced free end 41 and an elongated slot 43 centrally and longitudinally located therein so as to provide longitudinal movement of the pointer with respect to the rigid arm 38. Integrally mounted within rigid arm 38 is an alignment pin 42 and locking screw 44 which are received in the slot 43 as best seen in FIG. 1 in conjunction with FIG. 3.

Yoke 16 is preferably made of a size so as to normally be non-deformable and is provided with suitable means by which handle 12 may be pivotally attached at an end thereof. The yoke is further provided with a slot at the opposite end which receives resilient beam 30 therein. The slot of the yoke 16 is illustrated as being diametrically apertured to receive rivets 18. Suitably mounted on yoke 16 is a frame guard 24 preferably fabricated from sheet steel or the like and positioned as illustrated as by welding or the like so as to form a mount means for the indicator 20. The indicator 20 is provided with elongated slotted apertures through which there is received set screws 25 that provide a means for moving the indicator relative to the yoke 16 for the purpose of zeroing the instrument.

The indicator 20 is provided with a torque scale 21 along one side which is plotted to read torque directly. Located along an edge of the indicator 20 is a lever arm extension scale 22 which is plotted to enable the torque to be read from scale 21 for each lever arm extension value of scale 22 employed.

FIG. 2 shows a slotted pointer carrying a slot 143 in which is located locking screw 144 having locking nut 145 located thereon in a manner as previously described in conjunction with FIGS. 1 and 3. Located on the rigid arm of FIG. 2 is a scale 171 graduated in appropriate units to indicate the length of the extension that may be used in conjunction with the torque wrench. By setting the pointer 140 to an appropriate position on the scale 171 in accordance with the length of the extension lever employed in conjunction with the torque wrench head 32, the force exerted in torquing a fastener can accordingly be directly measured by a conventional scale attached to the torque wrench in a manner previously discussed in conjunction with FIG. 1.

The indicator 20 of the present invention alternatively can be made integrally with the pointer 40 so as to move with respect to a stationary pointer or needle located near the handle 12. For example, indicator 20 of FIG. 1 could alternatively be rigidly attached on the pointer at 41, and a fixed pointer could be rigidly attached to the yoke 16 to thereby provide relative movement between the resilient beam 30 and the indicator. The indicator could also be made to slide along yoke 16 while using a conventional stationary pointer. This would also provide relative positioning of pointer with respect to scale.

The relationship of the head 32 and handle yoke assembly of the torque wrench could be reversed, whereby the tool would still function in the manner disclosed; although, such an arrangement would provide a tool which may not be suitable for most conventional torquing op erations.

A cylindrical type of scale may alternatively be employed whereby the scale has a rotational position associated with any given lever arm extension. In such an embodiment, the scale could readily be rotated to any one of a multiplicity of positions each of which would represent a different lever arm extension tool attached to the head portion of the wrench. Such a configuration of the scale would enable one to readily read directly from the appropriate scale the exact torsional force being used to torque a fastener or the like.

Still another scale which alternatively may be used in lieu of the preferred embodiment described above, is an elastic or expandable scale which can be adjusted for various lever arm extensions to enable direct reading by correlating the lever arm extension with the amount of stretch or expansion of the elastic or expandable scale. The expandable scale is suitably mounted on the guard attachment frame 24 and provided with means correlated with the rigid arm 38 that would extend or expand the scale in accordance with the length of the extension used in conjunction with the torque wrench.

The torque wrench illustrated in the preferred embodiment illustrated in FIGS. 1 and 3 may be readily adjusted for direct scale reading using any lever arm extension tool within the designed range of the indicator. The torque scale 21 may be calibrated in any desired units consistent with the design of the resilient beam 30. In the case where a lever arm extension is not attached at head 32, the pointer 40 must be adjusted by loosening the nut 45 and positioning pointer 40 at the zero mark on the lever arm extension scale 22, as will be pointed out in greater detail later on. The integral square 34 is provided with a suitable socket, such as found in any conventional tool box, that will suitably fit the particular fastening means or device being torqued. The torque applied by the wrench to the fastener would then be read directly from scale 21 in accordance with the calibrated figures on indicator 20 located along lines drawn longitudinally of the rigid arm 38. In the case where a lever arm extension is used, the tool may be suitably fastened at the head 32 by snapping the tool into place on the integral square shank where it will be releasably held in proper position by the spring pressed latch plunger 36, as is well known in the art. The effective length of the lever arm extension tool is next set on the lever arm extension scale 22 by loosening the compensator rigid arm and pointer locking nut 45 and positioning the reduced end 41 of the pointer to the value on scale 22 in accordance with the effective length of the lever arm extension. The torque applied to the fastener may then be directly read on torque scale 21 in accordance with the value indicated by the reduced portion 41. Thus it should be evident that the sliding mechanism, that is, the compensator 10 including pointer 46, may be adjusted throughout its range represented by the lever arm extension scale 22 so as to position the pointer portion 41 in accordance with the length of the lever arm extension tool being employed. Any lever arm may be used which has a length that falls within the range provided by the scale 22 of the indicator.

The novel lever arm compensator device of the instant application may be incorporated into the indicator and scale of an existing type of torque wrench. From FIG. 1 it is evident that as the sliding mechanism of the lever arm compensator is adjusted through its range on the lever arm extension scale 22 of the indicator 20, the position of the pointer with respect to torque scale 21 is continuously changed. This action makes it possible to mark off a lever arm extension scale 22 in arbitrary length units on the stationary part of the pointer arm as seen at 4 171 in FIG. 2, or longitudinally on indicator 20 as seen at 22 in FIG. 1; and then, with the use of a torque calibrator and a number of lever arm extensions within the desired range, torque scale 21 can be plotted to read the torque directly for each lever arm extension tool used. This is possible since a different portion of torque scale 21 is used for each value set on the lever arm extension scale 22. Points of equal torque value are then joined to complete the torque scale as illustrated in the drawing. Assume, for a specific example, that the instant novel torque wrench is desired to be used in directly tightening a fastener such as a standard "7' inch hex-nut wherein a lever arm extension tool is not required. A standard socket from a tool kit, such as a 6 or 12 point socket, with a female drive adapted to mate the integral square shank 34, would preferably be used with the reduced end 41 of pointer 40 aligned at zero on the lever arm extension scale 22 to thereby directly give the torque units applied to the fastener from torque scale 21.

Where the use of an extension tool is required in conjunction with the novel torque wrench, the lever arm compensator is adjusted by changing the effective length of the compensator whereby the pointer is thereby aligned along the proper value of scale 22 representative of the in-line length of the lever arm extension tool that is added to the torque wrench, i.e., the actual increase in effective in-line length of the wrench taken along a line from the applied force at handle 12 to the centerline of the fastener being torqued.

As another specific illustrative example, an extension tool is required having an effective increase of in-line length equivalent to 2 inches. The compensator 10 is accordingly extended from the zero position, as recited in the above example, to the 2 inch position, as seen in FIG. 1, along scale 22 of indicator 20. The fastener is then torqued to the desired value as read on scale 21. Hence the instant novel torque wrench provides a means by which the applied torque may be read directly when the wrench is used with or without an extension tool, merely by adjusting the pointer of the compensator in accordance with the particular extension tool used in the torquing operation.

This unique capability is provided by the before-mentioned adjustable pointer-compensator, that replaces the conventional fixed pointer on presently available torque wrenches, combined with a novel precalibrated multiple scale unit. Any configuration of the torque wrench adaptor or lever arm extension tool may be employed so long as the driven end of the adapter is properly mated to the integral square 34 and the effective straight line dimension between the fastener and the integral square shank is known, so as to enable the slidable pointer 40 of compensator 10 to be properly positioned along the scale 22.

Having thus described my invention, what I claim as new and desire to secure and protect by Letters Patent of the United States is:

I claim: 1. In a torque measuring tool having a resilient beam with a work-engaging means at one end thereof and a handle for applying a force at the other end, the improvement for use with an extension arm at the workengaging end comprising:

an indicator carried at the handle end of the beam, said indicator including a first calibration scale in torque units and a second calibration scale located laterally of said first calibration scale and in units comprehending different lengths of extension arms;

and an extension lever arm compensator means including a rigid arm portion carried by and integrally attached to the work-engaging end of the beam, said compensator normally being coextensive and aligned with the resilient beam;

said compensator including an elongated pointer superimposed on and manually adjustable longitudinally of said rigid arm along said second scale to thereby coordinate the measured torque on the first scale with an extension arm at said work-engaging means.

2. In a torque measuring tool having a resilient beam with a work-engaging means at one end thereof and a handle affixed to the beam by a yoke for applying a force at the other end the improvement comprising:

an extension lever arm compensator means including a rigid arm portion of a length less than that of said beam, carried by and integrally attached to the workengaging end of the beam, said compensator normally being coextensive and aligned with the resilient beam;

said compensator including an elongated pointer aligned with said rigid arm and having a longitudinally extending slot;

a pin and a fastener means received in said slot and rigidly atfixed to said rigid arm to provide for longitudinal movement of said pointer with respect to said rigid arm;

an indicator adjustably afiixed to the yoke, aligned with the free end of said pointer and including a graduated first scale extending laterally of the pointer to thereby give an indication of the torque applied through said tool;

and a second scale extending longitudinally of said pointer and adapted to correlate the length of the compensator with the length of an extension attached at the Work-engaging means;

whereby an extension tool may be used in conjunction with the torque tool by coordinating the effective length of the torque tool with the longitudinal position of the pointer on the second scale to thereby directly read the torque applied through said tool.

3. In a torque measuring tool having a resilient beam with a work-engaging means at one end thereof connected to a lever arm extension which is in turn connected to a fastener to be torqued by a predetermined force applied to a handle at the other end, the improvement comprising:

an extension lever arm compensator means including a rigid arm portion carried by and integrally attached to the work-engaging end of the beam, said compensator normally being coextensive and aligned with the resilient beam;

said compensator including an elongated pointer aligned with said rigid arm and including means adjustably attaching one end of said pointer to said rigid arm;

an indicator carried at the handle end of the beam;

and two calibrated scales graduated on said indicator,

each scale having coordinates extending therefrom in intersecting relationship; one of said scales lying laterally of said free end of said pointer to indicate the torque applied by the tool to the fastener;

and the remaining said scale lying longitudinally of the free end of said pointer to coordinate the compensator with the length of the extension lever arm to thereby regulate the true torque applied to the fastener;

the free end of said pointer being adapted to extend beyond said rigid arm in cooperation with said indicator and to move laterally of said beam upon deflection of said beam in proportion to the magnitude of a force applied to the handle to thereby give an indication on said indicator of the torque applied by the tool to the work at a point removed therefrom.

4. In a torque measuring tool having a resilient beam with a work-engaging means at one end thereof and a handle for applying a force at the other end, the improvement comprising:

an indicator carried at the handle end of the beam;

an extension lever arm compensator means including a rigid arm portion carried by and integrally attached to the Work-engaging end of the beam, said compensator normally being coextensive and aligned with the resilient beam;

said compensator including an elongated pointer aligned with said rigid arm and including means adjustably attaching one end of said pointer to said rigid arm;

said rigid arm being provided with a scale means having calibrations thereon to enable positioning said pointer with respect to said rigid arm to thereby maintain the ratio of the length of the compensator and tool of a value that will permit readability of the torque on said indicator when the tool is used in conjunction with an extension lever arm;

and the free end of said pointer being adapted to extend beyond said rigid arm in cooperation with said indicator and to move laterally of said beam upon deflection of said beam in proportion to the magnitude of a force applied to the handle to thereby give an indication on said indicator of the torque applied by the handle to the work at a point removed therefrom.

References Cited UNITED STATES PATENTS 2,277,700 3/1942 Guibert et a1. 116129 2,404,029 7/1946 Birk 73-139 2,647,485 8/1953 ONeill 116-129 2,888,825 6/1959 Kraift 73-139 RICHARD C. QUEISSER, Primary Examiner.

C. A. RUEHL, Assistant Examiner. 

